HUMAN MOVEMENT
2009, vol. 10 (2), 91–95
NO ASSOCIATION BETWEEN SKINFOLD THICKNESSES AND RACE
PERFORMANCE IN MALE ULTRA-ENDURANCE CYCLISTS IN A 600 KM
ULTRA-CYCLING MARATHON
DOI: 10.2478/v10038-009-0018-y
Beat Knechtle1, 2*, Patrizia Knechtle1, Thomas Rosemann2
1
Gesundheitszentrum St. Gallen, St. Gallen, Switzerland
2
Institute of General Practice and Health Services Research, University of Zurich, Zurich, Switzerland
ABSTRACT
Purpose. In long-distance runners, an association between skinfold thicknesses and running performance has been demonstrated.
Basic procedures. We investigated the relationship between skinfold thicknesses and race time in cyclists in an ultra-endurance
cycling race. In 28 ultra-endurance cyclists at the ‘Swiss Cycling Marathon’ over 600 km, skinfold thickness at 8 sites was measured
pre race. Single skinfold thicknesses, the sum of 8 skinfolds and percent body fat were correlated with total race time. Main findings.
The cyclists finished within 1.596 (296) min riding at an average speed of 26.8 (5.7) km/h. There was no correlation between single
skinfold thicknesses, the sum of 8 skinfold thicknesses and percent body fat with total race time. Conclusions. In male ultra-cyclists in
a 600 km ultra-marathon, no correlation between skinfold thicknesses and race performance has been detected as demonstrated
in long-distance runners.
Key words: anthropometry, ultra-endurance, body fat
Introduction
Ultra-endurance races are becoming more and more
attractive and an increasing number of cyclists intend to
start in ultra-cycling races such as the ‘Race Across
AMerica’ (RAAM) in the USA or ‘Paris–Brest–Paris’
in Europe. There is very limited data concerning anthropometry in ultra-endurance cyclists and a question
is whether a slim and light body, respectively low body
fat is of importance in finishing such an ultra-cycling
race.
In these ultra-cycling races, a considerable decrease
in body mass has been described [1, 2], as already stated
in shorter ultra-cycling races [3, 4]. In two case reports
[1, 2] and two field studies [3, 4], anthropometric data
including age, body mass, body height and body mass
index of the cyclist and the loss of body mass were provided. In the two case studies, the athletes were riding for
several days and lost substantially more body mass in the
form of body fat [1, 2] than the cyclists in the two ultracycling races of less than one and a half day [3, 4].
Regarding body fat, the relationship between skinfold thicknesses and endurance performance has been
* Corresponding author.
intensely investigated in long-distance runners. Hagan
et al. [5] demonstrated a correlation between the sum of
7 skinfold thicknesses and marathon performance time.
Total skin-fold, the type and frequency of training and
the number of years running were the best predictors of
running performance and success at the 10 km distance
according to Bale et al. [6]. In recent studies, a relationship between the thicknesses of selected skinfolds and
running performance has been demonstrated in top
class runners [7, 8]. In these studies, elite runners of
distances from 100 m to 10,000 m and the marathon
distance have been investigated [7, 8]. Arrese and Ostáriz [7] showed high correlations between the front
thigh (r = 0.59, p = 0.014) and medial calf (r = 0.57, p =
0.017) skinfold and 10,000 m running time. It is supposed that the thicknesses of the lower limb skinfolds
are the result of intense training in running [8].
The relationship between skinfold thicknesses and
race performance was investigated in all running distances from 100 m to 10,000 m in male top level athletes;
but not in ultra-endurance cyclists. We therefore investigated the existence of an association between skinfold thicknesses and race performance in male ultraendurance cyclists. Considering the fact that ultraendurance cyclists have to climb partly step ascents,
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B. Knechtle, P. Knechtle, T. Rosemann, Skinfold thickness in ultra-cyclists
low body fat respectively low skinfold thicknesses
would probably enhance performance and the training
in the preparation for the race should lead to an association between skinfold thickness and training volume,
respectively intensity in training.
We therefore hypothesized to find a correlation between skinfold thicknesses, respectively the sum of
skinfold thicknesses and race performance. Furthermore, training volume and thickness of skinfolds should
show an association.
Material and methods
Subjects
The organiser of the ‘Swiss Cycling Marathon’ contacted all participants of the race in 2007 by a separate
newsletter, three months before the race, in which they
were informed about the study. Athletes were asked
about their average weekly training volume in hours
and kilometres in cycling over the last 3 months in the
preparation for the race. During these 3 months prior to
the race, each athlete maintained a comprehensive
training diary consisting of daily workouts with distance and duration in order to determine speed in cycling during training. Additionally, they reported their
training volume in cycling kilometres over the past 12
months before the race. A total of 123 male non-professional cyclists started in order to qualify for the ultracycling marathon ‘Paris–Brest–Paris’. Thirty-six male
athletes were interested in our investigation. Subjects
were informed of the experimental risks and gave informed consent prior to the investigation. The investigation was approved by the Institutional Review Board for
use of Human subjects. Twenty-eight cyclists with mean
(SD) 42.3 (7.3) years, 78.3 (7.5) kg body mass, 1.81
(0.07) m body height and a BMI of 24.2 (1.9) kg/m2 out
of our study group finished the race successfully.
The race
The ‘Swiss Cycling Marathon’ took place from the
29th to 30th June 2007 as a non-stop ultra-cycling race
from the outskirts of Bern (Switzerland) over the border
to Germany, then along Lake Constance into the Alps
of Eastern Switzerland and back to Bern. During this
600 km race, the athletes had to climb a total altitude
of 4,630 m. The weather in Bern was fine and sunny,
with 22 °C during the day and 11 °C in the night. Athletes
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were allowed to have a support crew with a car. About
every 60 km, a checkpoint was set where every cyclist
had to stop and register. Besides, food and drinks were
served at these aid stations. A time limit was set at 40
hours.
Measurements and calculations
Before the start of the race, every participant underwent anthropometric measurements in order to determine body mass, body height and skinfold thicknesses
at 8 sites in order to calculate the sum of 8 skinfold
thicknesses and percent body fat. Body mass was measured using a commercial scale (Beurer BF 15, Beurer,
Ulm Germany) to the nearest 0.1 kg. Body height was
measured using a stadiometer to the nearest 1.0 cm.
Skinfold thicknesses of pectoralis, midaxillary (vertical), triceps, subscapular, abdominal (vertical), suprailiac (at anterior axillary), thigh and calf were measured
using a skinfold calliper (GPM-Hautfaltenmessgerät,
Siber & Hegner, Zurich, Switzerland) to the nearest
0.2 mm at the right side of the body. Percent body fat
was calculated using the following anthropometric formula for men: Percent body fat = 0.465 + 0.180(Σ7SF) –
0.0002406(Σ7SF)2 + 0.0661(age), where Σ7SF = sum of
skinfold thickness of pectoralis, midaxillary, triceps,
subscapular, abdomen, suprailiac and thigh mean, according to Ball et al. [9]. This formula was evaluated in
160 men aged 18–62 years and cross-validated using
DXA (dual energy X-ray absorptiometry). The mean
differences between DXA percent body fat and calculated percent body fat ranged from 3.0% to 3.2%. Significant (p < 0.01) and high (r > 0.90) correlations existed between the anthropometric prediction equations
and DXA. One trained investigator took all skinfold
measurements as inter-tester variability is a major
source of error in skinfold measurements. Intra-tester reliability check was conducted on 27 male runners prior to
testing. No significant difference between the 2 trials
for the sum of 8 skinfolds was observed (p > 0.05). The
intra-class correlation was high at r = 0.95. The same
investigator was also compared to another trained investigator to determine objectivity. No significant difference existed between testers (p > 0.05). The skinfold
measurements were taken once through entire 8 skinfolds and then repeated 3 times by the same investigator; the mean of the 3 times was then used for the analyses. The timing of the taking of the skinfold measurements was standardised to ensure reliability. According
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B. Knechtle, P. Knechtle, T. Rosemann, Skinfold thickness in ultra-cyclists
Table 1. The correlation of the anthropometric variables with speed in training,
average weekly training volume, race time and speed in the race
Variable
SF pectoral (mm)
SF axillar (mm)
SF triceps (mm)
SF subscapular (mm)
SF abdominal (mm)
SF suprailiacal (mm)
SF thigh (mm)
SF calf (mm)
Sum of 8 skinfolds (mm)
Percent body fat (%)
Pre race
Speed in training
(km/h)
Training volume
(km/week)
Race time
(min)
Speed in the race
(km/h)
8.4 (3.2)
9.4 (3.5)
9.1 (3.2)
12.1 (4.9)
20.2 (8.2)
16.4 (5.6)
14.0 (5.5)
7.1 (3.1)
96.7 (28.7)
17.3 (3.7)
–0.19
–0.16
–0.16
–0.28
–0.25
–0.21
–0.20
–0.23
–0.28
–0.28
–0.24
–0.12
–0.16
–0.16
–0.24
–0.26
0.24
0.02
–0.16
–0.17
0.29
0.23
0.30
0.17
0.28
0.20
0.15
0.28
0.30
0.35
–0.36
–0.29
–0.34
–0.22
–0.36
–0.23
–0.20
–0.35
–0.38
–0.42
Results are presented as mean (SD); R-values are presented for all variables; no significant association has been found
2300
2300
to Becque et al. [10], readings were performed 4 s after
applying the calliper.
2100
2100
1900
1900
Data are presented as mean (SD). Speed in training
and speed during race were compared with Wilcoxon
signed rank test. The coefficient of variation (CV% = 100
× SD/mean) of performance for total race time was calculated. The Pearson’s correlation coefficient was used to
test for univariate associations between speed in training
and speed in the race with the anthropometric variables.
Bonferroni correction was used to compensate for multiple testing effects. Significant p-values after Bonferroni
correction were assumed at a level of p < 0.005 (n = 10
tests for the relationship between race time with the anthropometric variables, 8 single skinfolds, sum of 8 skinfolds and percent body fat).
Race
time
Race
time(min)
(min)
Statistical analysis
1
700
1700
1500
1500
1300
1300
1100
1100
900
900
700
700
100
100
200
200
300
300
400
400
500
500
600
600
700
700
Average
weeklytraining
training volume
(km)
Average
w eekly
volum
e (km )
Figure 1. The average weekly training volume showed
no association with race performance (r = –0.05, p > 0.05)
2300
2300
2100
2100
Results
Race
Racetime
time (min)
(min)
1900
1900
In the preparation of this race, the athletes were cycling 13.1 (4.7) h per week and were completing 340
(117) km. During training, the cyclists were riding at an
average speed of 26.8 (5.7) km/h, significantly faster
compared to speed in the race with 23.2 (3.7) km/h. The
athletes reported a yearly training volume of 11,100
(4,700) cycling kilometres. The cyclists finished the
race in a mean time of 1,596 (296) min (CV = 17.9 %).
The relationship between the skinfold thicknesses and
training volume, speed in training, race time as well as
speed in the race is shown in Tab. 1. No association
could be shown between the thickness of the single
1700
1700
1500
1500
1300
1300
1100
1100
900
900
15
15
20
20
25
25
30
30
35
35
40
40
Average
speed in
(km/h)
Average
speed
intraining
training
(km /h)
Figure 2. The intensity during training showed
no association with race performance (r = –0.01, p > 0.05)
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B. Knechtle, P. Knechtle, T. Rosemann, Skinfold thickness in ultra-cyclists
skinfolds, the sum of 8 skinfold thicknesses and percent
body fat neither for speed in training and racing nor for
training volume in cycling kilometres and total race
time. Neither average weekly training volume (Fig. 1)
nor average speed in training (Fig. 2) were related to
race performance.
Discussion
In contrast to male long-distance runners [7] where
a correlation between skinfold thicknesses at the lower
limb and running performance has been shown, we
could not detect an association between thickness of selected skinfold sites and race performance in these male
ultra-endurance cyclists. A possible explanation for these
different findings might be the kind of exercise since
Arrese and Ostáriz [7] and also Legaz and Eston [8] investigated runners while we investigated cyclists. Running might lead to an increased decline in body fat since
fat oxidation is increased during running compared to
cycling [11, 12]. This might explain why Legaz and Eston [8] found an association between training volume
and decrease in the sum of 6 skinfold thicknesses.
Arrese and Ostáriz [7] showed high correlations between the front thigh (r = 0.59, p = 0.014) and medial
calf (r = 0.57, p = 0.017) skinfold thickness and 10,000 m
running time in male high-level runners; however, no
association between the sum of 6 skinfold thicknesses
and both 10,000 m (r = 0.42, p > 0.05) and marathon (r =
0.13, p > 0.05) performance time. Running training
leads to a decrease in skinfolds of the lower body. Legaz
and Eston [8] could demonstrate a significant decrease
in abdominal skinfold thickness (p = 0.032), front thigh
skinfold thickness (p = 0.008), medial calf skinfold
thickness (p = 0.028) and the sum of 6 skinfold thicknesses (p = 0.037) due to running training. Both in running and cycling muscles of the lower limb are used;
a relationship between training and skinfold thickness
at the lower limb has been found in long-distance runners, however, not in these ultra-endurance cyclists.
Obviously cycling is not so intense and muscular work
of these specific muscle groups seems to have no effect
on the adipose subcutaneous tissue.
Legaz and Eston [8] suggested that intensity in training is related to thinner skinfolds. Training resulted in
a significant decrease in the sum of 6 skinfold thicknesses and the thickness of abdominal, front thigh and
medical calf skinfold in their investigation over a 3 year
period. They concluded that the loss in body fat was
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specific to muscular groups used during training. We
would therefore expect that ultra-endurance cyclists using their legs would show an association between the
skinfold thickness of the lower limb such as thigh respectively calf and training volume or intensity during
training. However, we could not find a relationship between average weekly training volume and training intensity with skinfold thickness (Tab. 1).
Arrese & Ostáriz [7] and also Legaz and Eston [8]
did not report intensity or volume in training during
running in their athletes. Training volume in our ultraendurance cyclists was presumably too low to have an
effect on body fat. On average, our ultra-cyclists trained
for 340 km per week in the specific preparation for this
particular race. This would amount to a calculated average yearly volume of 17,680 km. However, the athletes
reported a yearly training volume of 11,100 (4,700) cycling kilometres in the preparation for the race. This
value corresponds to the average yearly volume of
a recreational ultra-endurance cyclist in an ultra-cycling
marathon [13], whereas an elite professional road cyclist
trains for about 24,000 kilometres during one season
[14]. Since ultra-endurance events are not attractive for
professional road cyclists, only recreational athletes
race in these events. The fact of finding no association
between both training volume (Fig. 1) and intensity during training (Fig. 2) with race performance might be
explained.
A limitation of this investigation might be a rather
small sample size of athletes. Unfortunately, the number
of participants in ultra-endurance races is rather low
compared to contests of shorter distances. Therefore the
available data is small and statistical power is less than
in other studies, such as the one performed by Arrese
and Ostáriz [7] with 130 male runners. In contrast to the
latter study, the volunteers in this study were part of the
participants of the competition and the number of subjects was definitely limited to that number. Therefore,
the power of the current study could not be increased by
the number of participants. Arrese and Ostáriz [7] investigated a total of 130 athletes; however, in their subgroups, smaller sample sizes of 16 to 24 athletes were
analysed. Likewise, Legaz and Eston [8] investigated
a small group of 24 male runners. Coefficients of variance (CV) of performance in the male runners in Arrese
and Ostáriz [7] varied between 2.13% and 3.36% whereas
we had a CV of 17.9%. Presumably a larger cohort of
ultra-endurance cyclists could show associations. A longitudinal study with a larger sample of ultra-endurance
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B. Knechtle, P. Knechtle, T. Rosemann, Skinfold thickness in ultra-cyclists
cyclists could probably assess the influence of skin-fold
thickness on performance.
Conclusions
In summary, this study showed no association between skinfold thicknesses and race performance in
recreational male ultra-endurance cyclists in contrast to
high-level long-distance runners. A longitudinal study
to assess the influence of skinfold thickness on performance in a larger sample of ultra-endurance cyclists
including elite cyclists is recommended. Since neither
training volume nor intensity in training revealed an association with race performance, potentially other factors such as equipment, nutrition, previous experience
and motivation might be of importance to endure such
a competition.
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Paper received by the Editor: April 14, 2009.
Paper accepted for publication: June 15, 2009.
Address for correspondence
PD Dr. med. Beat Knechtle
Facharzt FMH für Allgemeinmedizin
Gesundheitszentrum St. Gallen
Vadianstrasse 26
9001 St. Gallen, Switzerland
e-mail: [email protected]
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